WASHINGTON — The Air Force's current fleet of aircraft is the smallest and oldest it has ever been, and although a plethora of acquisition programs are slated to update it with new capabilities, service officials are concerned about its ability to control the skies and strike targets at will.

The service is banking on future technologies that can bring additional firepower to the battlefield without having to buy new aircraft, relying instead on unmanned aerial systems (UAS), modified legacy planes and advanced weaponry.

"Warfare is still about amassing firepower at a time and place in space, whether it's in the air or on the ground," outgoing Air Force Chief of Staff Gen. Mark Welsh told Defense News in June ahead of his retirement later that month. "And amassing firepower means you need weapons, you need precision, and you need the ability to target."

"We have platforms and sensors that can provide that. We just don't have the mass firepower available in every scenario we might face because we have shrunk the size of our force," he said. "So if you can't bring as many airplanes to the fight, maybe you've got to figure a way to bring more weapons to the fight."

One of the most highly anticipated ways of doing that is the so-called "arsenal plane" under development by the Pentagon's secretive Strategic Capabilities Office. Defense Secretary Ashton Carter revealed the existence of the outfit, which seeks near-term advancements by modifying and repackaging existing technologies for new uses, earlier this year.

SCO's arsenal plane concept will take an older airframe — the office has not yet divulged which platform is to be used — and load it with a large amount of precision-guided munitions. During combat, fifth-generation fighters would penetrate the enemy's airspace and provide targeting information to the arsenal plane, which could then take out adversaries from standoff distances, said SCO director William Roper during the Defense One Technology Summit.

Welsh said he wasn't sure if the arsenal plane concept would ultimately be adopted by the Air Force, but that it "absolutely" should be developed further because of the service's dire need for more firepower.

"Let's say we get no new force structure for the next twenty years and we're stuck with what we have, what we have on the books today. If you want to do air superiority on a broader scale than a hundred and eighty-seven F-22s will allow you to do it, the real thing you run out of at first in the forward edge of the battle space is weapons," he said.

SCO also has high hopes for the "loyal wingman" concept, which gives pilots in manned fifth-generation planes control of an unmanned fourth-generation fighter — allowing, for example, a pilot to fly his F-35 and an unmanned F-16 simultaneously.

"We're probably not ready to build an unmanned fighter that just goes out alone. We're going to have to team it with a piloted system," Roper said. "What an unmanned system really gives us is the ability to do maneuvers that we wouldn't do with a pilot, carry payloads that might not be safe to have on a manned system, and to put in a little more risk than we would put when we put a pilot in."

Both SCO and the Defense Advanced Research Projects Agency (DARPA), which aims to develop long-term breakthroughs, are focusing on technology related to swarming unmanned aerial systems, or UAS. One of SCO's projects involves the creation of cheap, expendable micro-drones that can be carried and deployed by tactical aircraft, but do not need to be recovered, Roper said.

On the other side of the technology curve is DARPA's Gremlins program, which would make deployable UAS recoverable, allowing the services to operate unmanned systems with more expensive payloads, said its deputy director, Steven Walker. Phase one contracts for concept development have been awarded to Composite Engineering, Dynetics, General Atomics and Lockheed Martin.

Other technologies DARPA is working on include software to aid the decision making of pilots in manned-unmanned teams, as well as payloads that would give UAS different effects, such as electronic warfare capabilities, he said at the Defense One event.

The agency also is investing heavily in hypersonic weapons, including a hypersonic air-breathing missile and a boost-glide vehicle, with the hopes that these super-fast and maneuverable munitions increase the survivability of aircraft. Walker stressed that these weapons will become available in the near future, calling them a "today" technology.

"I would say we're closer on hypersonics than we are with directed energy in terms of making that a real capability" he said.  "I look forward to that being a key part of any U.S. air posture in the future."

Twitter: @ValerieInsinna